Dual-acting, redundant, hydraulic cylinder arrangement for air and spacecraft

ABSTRACT

A dual-acting, redundant hydraulic cylinder including a first hydraulic cylinder system arranged radially around a second hydraulic system. Each of the systems is provided with a common piston. In accordance with the illustrated embodiment, the piston is constructed so that the working area associated with the first hydraulic system is approximately equal to the working area defined by the second hydraulic system.

United States Patent Inventor Edmund Norbert Mahler Landham-West, Germany Appl. No. 753,659

Filed Aug. 19, 1968 Patented Mar. 2, 1971 Assignee Entwicklungspring Sud G.m.b.11.

Munich, Germany Priority Aug. 31, 1967 Germany E34700 DUAL-ACTING, REDUNDANT, HYDRAULIC CYLINDER ARRANGEMENT FOR AIR AND SPACECRAFT 3 Claims, 2 Drawing Figs.

US. Cl 1.

Int. Cl Field of Search 91/411, 60/97, 92/151 FOlb 7/00 Primary Examiner-Edgar W. Geoghegan Attorney-William K. Serp ABSTRACT: A dual-acting, redundant hydraulic cylinder including a first hydraulic cylinder system arranged radially around a second hydraulic system. Each of the systems is provided with a common piston. In accordance with the illustrated embodiment, the piston is constructed so that the working area associated with the first hydraulic system is approximately equal to the working area defined by the second (P); 244/78 hydraulic system.

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2 Sheets-Sheet 2 FIG.2

DUAL-ACTING, REDUNDANT, HYDRAULIC CYLINDER ARRANGEMENT FOR AIR AND SPACECRAFI BACKGROUND OF THE INVENTION This invention relates to a dual-acting, redundant hydraulic cylinder particularly adapted for use with air and spacecraft. Such cylinders are frequently used as hydraulic actuators.

Various types of actuators which produce equal forces and velocities in both longitudinal directions and in any attitude are known in the prior art. Generally, such actuators include a piston rod having the shape of a cylinder with its closed end disposed outwardly and its open end disposed inwardly of the device. Such arrangements display a particular disadvantage in that they lack a fail-safe or safety arrangement. For example, should the hydraulic control circuit serving to extend the piston fail during the working cycle when the piston is not in its end position, it is often possible to retract the piston to its original starting position by means of the secondary hydraulic circuit. However, under such circumstances, the entire system is no longer operative.

For air and spacecraft, a failure of thistype can have grave consequences. It is the objective of the illustrated embodiment to eliminate this disadvantage by providing a dual-acting, redundant hydraulic cylinder system in a compact radial arrangement.

The illustrated embodiment achieves this objective by means of a hydraulic cylinder system which is arranged radially around a second hydraulic system and wherein the piston is provided with an integral shape for use in both systems. In accordance with the illustrated embodiment, both hydraulic systems are combined into a single structural unit, and the effective working area of the piston associated with the first hydraulic system is equal to the effective working area of the second hydraulic system.

Additional features and advantages of the invention will become apparent with reference to .the following description and accompanying drawings which show an illustrative embodiment of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a hydraulic cylinder system embodying certain features of this invention.

FIG. 2 is a schematic, operational diagram of a system utilizing the cylinder of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT With particular reference to FIG. 1, a piston 20 is positioned within a cylinder which defines two coaxial chambers l1 and 12. The piston 20 is constructed so that a working area 21 is associated with a first hydraulic system and defined by the walls of the cylinder chamber 11, whereas a corresponding working surface 25 'is associated with a second hydraulic system and defined by an inner wall of the cylinder chamber 11. The cylindrical wall 22 of the piston divides the chamber 11 into two chambers 13 and 14 of generally equal size and defines working surfaces 23 and 24 in chambers 13 and 14 respectively. The arrangement according to the illustrated embodiment is such that the displaced volume of the cylindrical chamber 1] equals that of the cylindrical chamber 12, whereas the volume of the cylindrical chamber 13 equals that of 14. Thus, the chambers 11 and 13 are referred to as the first hydraulic system, and the chambers 12 and 14 as the second hydraulic system. In this manner, two independent hydraulic systems have been created in an integral arrangement.

Referring now to FIG. 2, the dual-acting cylinder of FIG. 1 is shown in a system employing valves 40 and 42, each of which are 4-way, Ii -position blocked-center valves which are standard in the hydraulic arts. Lines 30 and 35 are fluid pressure lines leading from a suitable source of hydraulic fluid to the valves 40 and 42, respectively, and lines 31 and 34 are exhaust lines. The valves as shown In FIG. 2 are in the centerblocking position, meaning that nofluid can enter or leave the dual-acting cylinder. The valves are shifted by solenoids 38 and 39 which are energized by means of switch 50. Lines 32, 33, 36 and 37 extend from valves 40 and 42 to chambers 13, 11, I4 and 12, respectively. Consequently, when the valves are in the far left position, chambers 11 and 12 are pressurized simultaneously with the fluid action on working surfaces 21 and 25 thereby driving the piston 20 to the left or to the outward position. At the same time, chambers 13 and 14 are exhausted. When the valves are in the far right position, chambers l3 and 14 are simultaneously pressurized with the fluid acting on working surfaces 23 and 24 while chambers 11 and 12 are exhausted, thereby causing the piston to move to the right or to the nested position. It is to be understood that the valves are operated simultaneously and are always in the same corresponding position. As mentioned earlier, one hydraulic system includes chambers 11 and I3 and the other hydraulic system includes chambers 12 and I4 and the associated working surfaces. Further, it is to be understood that the switch causes the simultaneous actuation of the solenoids 38 and 39 which causes the valves to shift in unison. It is to be understood that the system shown in FIG. 2 can be combined in a unitary structure; that is, the valves can be attached to or otherwise be made part of the cylinder housing for purposes of space conservation.

lclaim:

1. A dual-acting, redundant hydraulic cylinder system particularly adapted for air and spacecraft comprising a first hydraulic system and a second hydraulic system each including a source of pressurized hydraulic fluid and a control valve, a common piston and cylinder for each of said systems, said piston having a pair of effective working areas for each of said systems, means communicating said common piston and cylinder to said source through said control valves, and means for actuating said valves whereby said systems cooperate to drive said common piston in the same direction.

2. The apparatus of claim 1 wherein the effective working area of the common piston subjected to pressure in the first hydraulic system is equal to the effective working area of the common piston subjected to pressure in the second hydraulic system.

3. A system as defined in claim 1 wherein said common piston and cylinder is a double-acting piston and cylinder and said valves are 4-way valves. 

1. A dual-acting, redundant hydraulic cylinder system particularly adapted for air and spacecraft comprising a first hydraulic system and a second hydraulic system each including a source of pressurized hydraulic fluid and a control valve, a common piston and cylinder for each of said systems, said piston having a pair of effective working areas for each of said systems, means communicating said common piston and cylinder to said source through said control valves, and means for actuating said valves whereby said systems cooperate to drive said common piston in the same direction.
 2. The apparatus of claim 1 wherein the effective working area of the common piston subjected to pressure in the first hydraulic system is equal to the effective working area of the common piston subjected to pressure in the second hydraulic system.
 3. A system as defined in claim 1 wherein said common piston and cylinder is a double-acting piston and cylinder and said valves are 4-way valves. 